Propeller construction



June 26, 1945. TROLLER I 2,378,958

PROPELLER CONSTRUCTION Filed Dec. 11, 1942 2 Sheets-Sheet 1 IN V EN TOR.

BY Mir June 26, 1945. T. H. TR OLLER 2,378,958

PROPELLER CONSTRUCTION Filed Dec. 11, 1942 2 Sheets-Sheet 2 INVENTOR.7mm ,4, 41m

. 9 1 k104i m Patented June 26, 1945 PROPELLER CONSTRUCTION i Theodor H.Troller, New Philadelphia, Ohio, as: signor to La-Del Conveyor &Manufacturing Company, a corporation of Ohio Application December 11,1942, Serial No. 468,651

11 Claims. (01. 230 114) Myinvention relates in general to variablepitch propellers and more particularly to the improvementof a rim and afitted blade construction adapted to give improved operatingcharacteristics.

An object of my invention is the provision of a variable pitch propellerhavinga rim with a cylindrical outer surface to which is rotativelymounted a fitted blade, wherein the outer cylindrical surface isprovided with a recess to receive the base portion of the blade, theconstruction and shape of the recess and of the lower base portion ofthe blade being such to provide a close clearancetherebetween to giveimproved operating characteristics.

Another object of my invention is the provision of a rim having asubstantially circular outer surface upon which one or more fittedblades drical outer surface instead of a non-circularconstruction whichwould tend to create turbulences I in the air stream.

Another object of my invention is the provision of a rim to whichvariable pitch propeller blades may be rotatively mounted wherein therim has a smooth cylindrical outer surface to minimize the turbulencesand the friction losses in the air stream. i

Another object of my invention is the provision of providing a'closeclearance between the base portion of the blades of a variable pitchpropeller and the rim to which the blades are rotatively mounted inorder to minimize noises and other air disturbances. a

Other objects and: a fuller understanding of my invention may be'had -byreferring .to' the following description and claims taken in conjunctionwith the accompanying drawings, in which:

. Figure 1 illustrates a front elevational view of Figure 2 isan,enlarged view taken along the line 2 2 of Figure 1 and showingprincipally the recess in the outer cylindrical surface of the rim 1 anda cross-section of the base portion of a blade which is arranged tofitin the. recess; I

Figure .3 is a cross-sectionalview taken along angle with respect to aplane the line 33 of Figure 2 and shows the close clearance which existsbetween =thebottom or base portion of the blade and the bottom of therecess; i

Figures l, 5 and 6 are viewssimilar to Figure 3, the figures being takenrespectively along the lines 4- 4, 55,and 66 of Figure 2;

Figures 7 and 8 are cross-sectional views taken respectively along thelines and 8-8 of Figure 2, the figures being shown in a matchedrelationship in order to showthe depth of the recess on the side edgewhich has the greater pitch passing through the zero pitch angleyandFigures 9 and 10 are'views taken, respectively, along the lines 99 and[0-H] of Figure 2, and

showing respectively the depth of the recessalong a the side edge whichhas the smaller pitch angle with respect to a planepassing through thezero pitch angle. r i i 1 i With reference to Figure 1, mylinvention maybe embodied in a variable pitch propeller comprising a plurality ofblades I5 rotatively mounted at spaced intervals to a rim I! which maybe driven by any suitable type of motive'power. The blades may. berotatively mounted to the rim by means of shanks l 8 which rotativelylit in sockets in the rim l1. The inner end of the shank l8maybe'actuated by a crank arm l9 to vary' the pitch angle of the blades.As illustrated, the crank arm l9:may be jointly operated by an axiallymovable control member or spider 20 actuated by a control lever 21 whichextends transversely of an air flow passage IS in which the propellerrevolves. The lower end of the control lever 2| mayrbe anchored to thebottom of the air flow passage l6 by means of a hinged connection 23 andtheupper end of the control lever 2| is arranged toextend externally ofthe air flow passage [6 so that as the control lever 2| isactuated backand forth the pitch of the propeller blades is accordingly varied. Theforward end of the rim I1 is provided with a nose-like cover 24 and anaxially movable control rod extends through the forward portion of thenose-like cover and inter-connects the control member 20 to theintermediate portion of the control lever 2! at the hinged connection22. The control mechanism for rotating the blades to vary the pitchthereof may be the same as that shown and described in an applicationexecuted concurrently herewith in the name of Thomas .0. Adams Jr. andTheodor H. Troller for an application entitled improvementin Adjusta'blepitch propeller mechanismand assignedto the assignee of thisapplication, While. I have illustrated a .fan .and the :bottom .of :therecesses. .icesses may the :cast or otherwise suitably proadjusted tovary the pitch thereof within predetermined limits.

The leading base portion 25 is arranged to-fit into a leading recess 21provided in the outer cylindrical surface of the rim -I"Iandthe-trailing base portion 26 of the bladeis arranged to fit in atrailing recess 28 mounted in the outer cylindrical surface of the rim;-H. The leading and trailing recesses 21 and 28 are Wide enough toallow the blade to be rotated to its predeterminedilimit of variablepitchangle. The leading recess 2'! is provided with atWO. side'edges2?!) and @Uandanend-edge -3l. The-bottom of the i leading recess 21 isindicated by the reference character '32.

leadingrecess -21 isdefined by the rotation of a The bottom surface .32of the generatrix aboutttheaxisof the hub. The-line 32in FiguresHTZ-andQ vwhicltiqdefines the bottom 'of .the leading .recess .at the plane vofthe particular -,cr.oss-sec.tion .is the generatrix. Similarly, thetrailing recess .28 is provided with side edges 33 and 34 and Ianendedge :35. The bottom of thetrailing recess ..-28.is indicated :by thereference character 36. The bcttomsurface 13.6 of the,trailing recess 28isldefined by .the rotation of ageneratrix about-the axis of .the .hub.The line 36. in-FiguresB; and which defines the bottorn of the.trailingrecessat the plane of theparticular 1c-rcssesection is :the.generatrix. As 'illustrated in Figures 3 to 10, inclusive, the sideedgesltlgand :33 are deeper than-the side edges SO-and :34. .In otherwords-the sideeedge'of'zthe leading and .trailing recesses 21 and 28which has the greater :pitch angle withrrespect 'to a plane :passingthrough :,the. .EZGIO pitch .angle :is deeper than-the :side v edges.whichzhaveithe smaller -zpitchangle. vThedeeper-side edges 1219 r and 3and the endedgesfll and3;5;are gradually sloped in order :to prevent.any abrupt change in the ,air flowuasthe air passes-along the outercylindrical surface of .the I1 and into they leadingandtrailing'recesses =2Land 2-8.

, The :bottom edge dfl of ztheleading base sporctionlziandxthe bottomedge 4|;of the trailing base portion :26 ."of the blades are shaped tosubstantially match the gradually sloped deeper side edges -29zand :33of the leading and .trailing recesses 1521 and :23, .see Figures '3 to6, inclusive.

As illustrated iniEigures 2 and :6,.the bottom edge 4110fthetrailingbase portion .26 is provided with can angularly disposed flange242- which is arranged :to :match the .deeper side edge .33 .of thetrailing recess 2-8. The bottomusurfaces 32 and 13B of the leading andtrailing .recessesJZl and 228 are varcuaterin a. longitudinal direction,and the botithezblade I 5, are correspondinglyarcuate to pro- .videaclose clearanceabetweenthebottom of the The revided in'the:rim-"|-:l."In the event the recesses .aretcast in the rimzli'Lithe patternsused'for making the casting .may have 1 the recesses provided therein.In 1 cutting the recesses in 1 the patterns, the, bottom -:surfaces.thereof may 7 be; determined gby .placingia given bladehaving a :givenunder ,the smaller pitch angle being shown by the dashdot line in Figure2. In this invention, it is to be understood that the leading andtrailing recesses 21 and 28 may have anyangular position with ;respectto the zero pitch line depending upon'the range through which the bladeis to be adjustably moved to obtain the most desirable operatingcharacteristics. In other words, the leading and trailing recesses 21and 28 may be shifted in a clockwise direction to have a smaller anglewithrespect to the zero;pitch line, or :they maybe shifted in acountersclockwiseudirection to have a .larger angle withrespeottoithevze o pitch line.

In my invention, I have no hole or-aperture extending through the :rimin theregionnof the base portion of the fan. blade. By eliminating thehole or aperture around the base portion .ofithe blade, I am able toproduce avariablezpitchdan construction which hasaminimumzofan'oises-and air disturbances. Also, in my invention .1 amable to employ a rim having an outer cylindrical smooth surface asdistinguished from =a runncircular rim: or arimzutilizin-gregulansurface. such for example, havingflatsurfacesradjacent the-lower edges of the-blades.

The leading and the trailingrecesses:2:l and 28 .may be cast in theouter cylindrical surface of the .rim and inasmuchzas -.there-.mays.b.ezirregularitiesin l the casting of the recesses, I :provide the shallowedges ;3-fl.and.-34. :In-ptherwords, in a theoretical sense, assumingthatzthe: bottom of the recesses and the DOttOmBdgQOIf thethladeswereperfectly smooth .and free. of mechanicalirregularities, then there"would Lbe :norneed :for

theshallowedges 30 .andM. Accordingly, the shallow edges :30 and 34 .are.made 'just mieep enough to take care of mechanicalzirregularities inthe casting-or.otherwise.manufacturingzof the recesses.

lnzoperation of myinvention, the-airfflows substantially uninterruptedlyover the .outer cylindrical surface of the rimll and producesaniimproved fan operation. The noise is reduced ito a low minimum and inaddition there is no mechanical concentration of stresses as is 28X-perienced in certain prior: art devices which employ a fairing or :othershell about the rim' through which the fan blades extend such, -*'forthe rim .or mounting to which it is rotatively connected. While I'haveshown the recesses 21 and 28 in a rim having an outer cyl'indricalsurface, it is to beunderstoodthatmy reoesses may :be utilized ina rimor mounting having a spherical, convex, or other curved surface andin-the claims the term -cylindrical-outer surface shall be interpretedto include spherical,

convex and all types of curved surfaces as well as-cylindrical surfaces.

Although I have described mybinvention with a certain degree ofparticularity, itis understood that the present disclosurehas been made;only by way of example and that numerous changes inthe details ofconstruction and the combination and arrangement of parts may beresorted to without departing fromthe spirit andgthe scope of theinvention as hereinafter claimed.

I claim as my invention:

1. In a variable pitch propeller mechanism, the improvement of a rim anda fitted blade construction, said rim having substantially a cylindricalouter surface, said blade being rotatively mounted about anoutwardlyextending axis in the-rim for adjusting the blade pitch withinpredetermined limits and having a leading base portion and a trailingbase portion extending in substantially opposite directions from saidaxis, said outer surface of the rim having a leading recess extendingforwardly from said axis to receive the leading base portion of theblade and having a trailing recess extending rearwardly from said axisto receive the trailing base portion of the blade, the bottom surfacesof said recesses being portions of surfaces of revolution, the axesthereof being the first mentioned axis, each surface of revolutionhaving a generatrix defining a line with a curvature close to thecurvature of the rim, the under surface of said leading base portion andof said trailing base portion being substantially congruent and coaxialwith the bottom surfaces of the leading and trailing recessesrespectively.

2. In a variable pitch propeller mechanism, the improvement of a rim anda fitted blade construction, said rim having substantially a cylindricalouter surfacasaid blade being mounted on therim and extending therefromand being rotatable about an axis for adjusting the blade pitch Withinpredeterminedlimits and having a leading base portion and a trailingbase portion extending in substantially opposite directions from saidaxis, said outer surface of the rim having a leading recess extendingforwardly from said axis to receive the leading base portion of theblade and having a trailing recess extending rearwardly from said axisto receive the trailing base portion of the blade, the bottom surfacesof said recesses being portions of surfaces of revolution, the axesthereof being the first mentioned axis, each surface of revolutionhaving a generatrix defining a line with a curvature close to thecurvature of the rim, the under surface of said leading base portion andof said trailing base portion being substantially congruent and coaxialwith the bottom surfaces of the leading and trailing recessesrespectively.

lution having a generatrix defining a line with a curvature close to thecurvature of the rim, the under surface of said leading base portion andof said trailing base portion being substantially congruent and coaxialwith the bottom surfaces of the leading and trailing recessesrespectively, each said recess having two side edges between which saidblade is adjustably moved to vary the pitch thereof, the side. edgewhich has the greater pitch angle with respect to a plane passingthrough the zero pitch angle beingdeeper than the other side edge.

4. In a variable pitch propeller mechanism, the improvement of a rim anda fitted blade construction, said rimv having substantially acylindrical outer surface, said blade being mounted on the rim andextending therefrom and being rotatable about an axis for adjusting theblade pitch within predetermined limits and having a leading baseportion and a trailing base portion extending in substantially oppositedirections from said axis, said outer surface of the rim having aleading recess extending forwardly from said axis to receive the leadingbase portion of the blade and having a trailing recess extendingrearwardly from said axis to receive the trailing base portion of theblade, the bottom surfaces of said recesses being portions of surfacesof revolution, the axes thereof being the first mentioned axis, eachsurface of revolution having a generatrix defining a line with acurvature close to'the curvature of the rim, the under surface of saidleading base portion and of said trailing base portion beingsubstantially congruent and coaxial with the bottom surfaces of theleading and trailing recesses respectively, each said recess having twoside 3. In a variable pitch propeller mechanism,

the improvement of a rim and a fitted blade construction, said rimhaving substantially a cylindrical outer surface, said blade beingmounted on the rim and extending therefrom and being rotatable about anaxis for adjusting the blade pitch within predetermined limits andhaving. a leading base portion and a trailing base portion extending insubstantially opposite directions from said axis, said outer surface ofthe rim having a leading recess extending forwardly from said axis toreceive; the leading base portion of the blade and having a trailingrecess extending rearwardly from said axis to receive the trailing baseportion of the blade, the bottom surfacesof said recesses being portionsof surfaces ofrevolution, the axes thereof being the first mentionedaxis, each surface of revosurfaces of the leading and passing throughthe zero edges between which said blade is adiustably moved to vary thepitch thereof, the side edge which has the greater pitch angle withrespect to a plane passing through the zero pitch angle being deeperthan the other side edge, said deeper side edges of the recesses beinggradually sloped to minimize air disturbances. l

5. In a Variable pitch propeller mechanism, the improvement of a rim anda fitted blade construction, said rim having substantially acylindricalouter surface, said blade being mounted on the rim andextending therefrom and being rotatable about an axis for adjusting theblade pitch within predetermined limits and having a leading baseportion and a trailing base portion extending in substantially oppositedirectionsfrom said axis, said outer surface of the rim having a leadingrecess extending forwardly from said axis to receive the leading baseportion of the blade and having a trailing recess extending rearwardlyfrom said axis to receive the trailing base portion of the blade, thebottom surfaces of saidrecesses being portions of surfaces ofrevolution, the axes thereof being the first mentioned axis, eachsurface of revolution having a generatrix defining a line with acurvature close to the curvature of the rim, the under surface of thesaid leading base portion and of said trailing base portion beingsubstane tially congruent and. coaxial with the bottom trailing recessesrespectively, each said recess having two side edges between which saidblade is adjustably moved to vary the pitch thereof, the side edge whichhas the greater pitch angle with respect to a plane pitch angle beingdeeper than the other side edge, each said recess also havingan endedge, said end edges and said deeper side edges of the recesses beinggradually sloped to minimizeair disturbances.

6. In a variable pitch propeller mechanism, the improvement .of a .rimand 1a fitted blade construction, said rim having substantially .acylindrical outer surface, said blade being mounted on the rimrandextending therefrom and being. rotatable about an axis for adjusting theblade pitch Within predeterminedlimitsand having a :base portionextending from .said axis, said rim having .a recessin the outersurfacethereof, the bottom of the .base portion of the blade fitting in thesaidsrecess, thebottom surface of said recess being a portion of aspherical surface of revolution, .the axis thereof coinciding with thefirst mentioned axis, said :spherical surface of revolutionlhaving ageneratrix clefining a line, said line intersecting isaidraxis at apointspaced at a'distancefrom the center of rotation of :the rimsubstantially equal to the radius of the rim, the bottom surface of saidbase portion being substantially congruent with the bottom surface ofthe recess, said recess having two side edges between which said bladeis adjustably moved to vary the pitchithereof.

7. In a variable pitch propeller mechanism,;the improvement of a rim and,a fitted blade :construction, said rim having substantiallyacylindrical .outer surface, saidblade'being mounted on the rim andextending therefrom and being rotatable about an axis for 'adiusting theblade pitch within predetermined rmas and having aleading base portionand a trailing base portion extending in substantially oppositedirections from said axis, said outer surface of the rim having aleading recess extending forwardly from said axis to receive the leadingbase portionof the blade and having a trailing recess extendingrearwardly fromsaid axis to receive the trailing base portion of theblade, the :bottom surfaces of said recesses being portions of surfacesof revolution, the axes thereof being thefirst mentioned axis, eachsurface of revolution having a, generatrix defining a line with acurvature close'to the curvature of the rim, the'under surface of saidleading base portion and of said trailing-base portion beingsubstantially congruent and coaxial with'the bottom surfaces of r theleading andtrailing recesses respectively, each said recess having twoside edges between which said blade-is .adjustably'moved to vary thepitch thereof, the sideed'ge which has thegreater pitch anglewith-respect to .a .plane,passing through the 'zero pitchangle beingdeeper than thevother side edge, said trailing base portion having anangularly disposed flange which substantially matches the side edge inthe trailing recess which, has the greater pitch angle.

8. In a variable pitch propeller 'mechanism, the improvement of a rimand a fitted blade construction, said rim having substantially ..acylindrical outer surface, and a socket therein, said blade having ashankv portion fitting 'lIllSELld socket and a base portionextending-outwardly from the rim, said blade being rotatable about anaxis for adjusting the blade pitch 'w-ithin predetermined -limits,,sai-drim having a-recess in the outer surface thereof and extending from theedges .of the socket, the bottom-of the base portion fitting in the saidrecess,zthe. bottom surface of said recess beinga portion .of aspherical surface of revolutiomtheaxis thereof coinciding with the firstmentioned axis, said spherical surface of revolution havinga generatrixdefining .a line, said line xintersecting-saidraxis at apoint spaced atadistance fromthe center of rotation of the rim substantially equaltocthe radius of the rim,the bottom surface of said base .p.ortion beingsubstantially congruent with thebottom surface of the recess, saidrecess having twoside edges betweenwh-ich :said blade is adjustablymoved to vary the pitch thereof.

9, In a variable pitch propeller :mechanism, the improvement of a rimand a fitted blade construction, said rim having substantially acylindrical outer surface, said blade being mounted on therim andextending therefrom and being rotatable about an axis for adjusting theblade pitch within predetermined limits and having a base portionextending from said said rimr having a recess in the outer surfacethereof,,the bottom of the base portion of the blade fitting, in thesaid recess, the bottom surface of said recess being a port-ion of asurface of revolution, the axes thereof being the first mentioned axis,the surface of revolution having ageneratrix defining .a line with acurvature close to the curvature of the rim, the under surface of saidbase portion being substantially congruent and o coaxial with the bottomsurface of the saidrecess. 10. In a variable pitch propeller mechanism,

the improvement of a rim and a fitted blade construction, said rimhaving substantially a cylindrical outer surface, said blade beingmounted on therim and extending therefrom and being rotatable about anaxis for adjusting the blade pitch within predetermined limits andhaving a base portion extending from said ,axis, said rim having anauxiliary surface, said' auxiliary surface being aportion ofa surface ofrevolution, the axes thereof being the first mentioned axis, the surfaceof revolution having-ta generatrix defining a line with the curvatureclose to the curvature of the rim, the undersurface of saidbase portionof the blade being dis posed close to and substantially congruent andcoaxial with said auxiliary surface.

11. In a variable pitchpropeller mechanism, the improvement of acylindrical rim. and; a fit-. ted blade construction, said blade beingmounted on the rim and extending-therefrom and being rotatable about anaxis for adjustingthe blade pitch withinpredeter-m-ined limits andhaving a leading base portion'and a trailing base portion extending insubstantially opposite directions from said axis, said rim having arecess on its outer surface to receive the base portions of the blade,said recess comprising a leading recess extending forwardly fromsaidaxisto receive the leading base portion of the blade and having atrailing recess extending rearwardly from said axis to receive thetrailing base portion of the blade, the bottom surfaces of saidrecessesbeing portions .of spherical surfaces of revolution, the axes thereofcoincidingwith the first mentioned axis, each spherical surface ofrevolution having a generatrixdefining a line,;eaoh said linerespectively intersecting said first mentioned axis at a point spaced ata distance from the center of rotation ofthe rim substantially equaltothe radius of the rim, the .bottom,- surfaceof said leading base portionand of ;-said trailing base portion being substantially congruent withthe bottom surfaces of the leading and trailing recess respectively,each saidrecess having two side edges betweenwhich said bladeisadjustably moved to vary the pitch thereof,

, ,THEODOR ,I-I. TROLLERQ,

